Anti-theft system

Asked by MrsMiller19 Feb 04, 2020 at 07:14 AM about the 2002 Cadillac DeVille Sedan FWD

Question type: Maintenance & Repair

I had to replace the alternator in my 2002
Cadillac deville. It won't start now. It says
service theft system. I have tried multiple
things to do this sometimes it starts but
when it does the dashboard and everything
goes crazy when I try to drive it and it feels
like it's going to stall out. when I try to start it
again it won't start. Still says service theft
system. How do I do this?

1 Answer

101,575

Could be a bad ECU. Diagnosing bad computer modules is usually beyond DIYers, have a shop look at it, if it is a bad ECU you may be able to buy a preprogrammed one online. Try looking up symptoms for a bad ECU or anti theft module and see if they match what is happening with yours.

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